Lance carriage stop



May 27, 1969 c, KANlA ETAL 3,446,316

LANCE CARRIAGE STOP Filed Aug. 1. 1966 Sheet of 5 INVENTORS Fi Robert C. Kuniu BY Thomas Greqord May 27, 1969 c, KAN ETAL 3,446,316

LANCE CARRIAGE STOP Filed Aug. 1, 1966 Sheet 2 of s 4s 48 K m I04 I04 l V IF v I A i I fi I r Q ,/90 a M I LIg j TLSZ /eo s4 E68 .1: O dq i 7o 5 us {To s 86 60 ea 2 1: ea 62 us 64 no no 0 s4 Fig. 2

I NVENTORS Robert C. Kuniu Thomas Greqord May 27, 1969 R. c. KANIA ET AL LANCE CARRIAGE STOP Sheet 4 of 5 Filed Aug. 1. 1966 Fig. 71.;

INVENTORS' Robert C Kama BY Thomas Greqord M y 1969 R. c. KANIA ETAL LANCE CARRIAGE STOP' Filed Aug. 1. 1966 urs Sheet INVENTORS Robert C. Kanio Thomas Gregord @f United States Patent Office 3,446,316 Patented May 27, 1969 US. Cl. 187-83 11 Claims ABSTRACT OF THE DISCLOSURE We disclose in a carriage and stopping mechanism therefor mounted for ascending and descending movement along guideways therefor having a plurality of spaced stops disposed along the length thereof and providing arresting surfaces for engaging and holding said carriage, the combination comprising retractable anchor means disposed between said carriage and said guideways and engageable with said stops to define a descending position of said carriage, a retractable drawbar member mounted for limited movement upon said carriage and engageable with elevating means for said carriage, means for coupling said drawbar member when so engaged to said anchor means to retain said anchor means in said retracted position thereof, biasing means coupled to said anchor means for urging said anchor means into engagement with said stops, said biasing means being operable upon disengagement of said elevating means from said draw-bar member and movement of said drawbar member to its retracted position, a stop bar movably mounted on said carriage, said anchor means :being movably mounted on said stop bar, and shock-absorbing means for limiting the movement of said stop bar, said anchor means being mounted on a stop bar, movably mounted on said carriage structure, and shock-absorbing means coupled to said stop bar.

Our present invention relates to an improved carriage for supporting a lance in the production of steel or similar production equipment, and more particularly to a stopping device which ensures that in the event of failure of the carriage raising and lowering mechanism, the carriage will become locked at a suitable elevation to preclude any possibility of injury to personnel or damage to plant equipment including the aforementioned lance and carriage.

In the steel making process, it has become a common practice to transfer the pig iron output of a blast furnace to an oxygen furnace for further purification thereof. In the latter furnace, oxygen is flowed over the surface of the charge during the process of converting the pig iron to steel. This process is sometimes referred to as the oxygen process and has become extensively and successfully utilized in the steel industry. The oxygen is supplied to the surface of the charge in the oxygen furnace from a lance which is lowered into the furnace and directs a stream of oxygen against the upper surface of the charge during the steel conversion operation. The oxygen lance is raised and lowered between respective retracted and operative positions thereof by means of a rectilinearly moving carriage, which is mounted for this purpose on vertical guideways. However, in the event of malfunctioning of the suspending or elevating means for the carriage, the freely falling carriage and lance presents a considerable hazard to operating personnel as well as entailing considerable damage to the carriage and lance. Moreover, extensive damage can be done to the oxygen furnace and the charge contained therein and to other associated plant components. In any event, substantial manufacturing delays and expenditure of labor are encountered in repairing or replacing the damaged carriage and lance before operation of the oxygen furnace can be resumed.

Conventional stop devices for vertically moving carriages frequently utilize electric solenoid or the like actuated anchorage means to suspend the carriage in the event of malfunctioning of its elevating mechanism. However, such arrangements are frequently unsatisfactory in steel making processes and similar manufacturing operations where the hot ambient temperatures encountered deteriorate the electrical insulating materials. Moreover, electrically actuated anchorage means are not desirable where the prime mover for the carriage means is not electrically powered, inasmuch as the electrically actuated anchorage means must perforce be electrically fail-safe.

Other conventional carriage anchorage means incorporate ratcheting structures, which not only are noisy but are unduly subject to wear.

Finally, it can be pointed out that prior carriage stop arrangements do not provide adequate means for limiting decelerating forces so that the freely falling carriage can be brought to rest without damage to the carriage and lance structure, or to other equipment associated therewith.

Our carriage stop means overcome these shortcomings, by providing a carriage stop arrangement which is entirely mechanical in operation, i.e., which does not require electromechanical linkages requiring an external power source. The carriage stop means forming the subject and our invention utilizes the weight of the carriage and the lance to overcome opposed biasing means which normally urges the anchor members of the carriage toward stop engaging positions. In furtherance of this purpose the carriage elevating means is secured to a drawbar or elevating member mounted on the carriage for limited movement so that movement thereof in one direction under impetus of the elevating means retains the anchor members in their inactive positions. However, under free fall conditions of the carriage, as when cables forming part of the elevating means are broken, the anchor member biasing means operates to move the elevating members in the other direction to release the anchor members.

In accordance with other features of our carriage structure one or more decelerational force limiting devices are coupled to the carriage and to the anchor members to prevent the build-up of destructive impact forces when the anchor members are actuated. In one arrangement of our carriage structure, the aforementioned force limiting means are engaged by a support frame or stop bar which is secured through shear members to the carriage structure. The anchor members are mounted upon the stop bar and any initial contact thereof with stops positioned along the vertical guideways of the carriage severs the shear members to permit limited movement of the stop bar relative to the carriage structure to render the force limiting devices operative.

These and other objects, features and advantages of our invention, together with structural details thereof, will be elaborated upon during the following description of certain presently preferred embodiments thereof.

In the accompanying drawings we have shown certain presently preferred embodiments of the invention wherein:

FIGURE 1 is an elevational view, partially in section, of a steel making furnace and lance therefor, and associated raising and lowering mechanism for the lance, incorporating the invention therein;

FIGURE 2 is a vertically sectioned view of the carriage structure illustrated in FIGURE 1 and showing the anchor members thereof in their withdrawn or inoperative positions;

FIGURE 3 is a vertically cross sectioned view of the carriage structure of FIGURE 2 taken along reference line III-III thereof;

FIGURE 4 is another vertically sectioned view of the carriage structure as shown in FIGURE 2 of the drawings but showing the anchor members thereof in their active or stop engaging positions; and

FIGURE 5 is a top plan view of the carriage structure as illustrated in FIGURES 2 and 3 of the drawings;

FIGURE 6 is a partially sectioned front elevational view of another form of the carriage structure and stopping mechanism therefor, and showing the stopping mechanism in its retracted or inoperative position;

FIGURE 7 is a partial, longitudinally sectioned view of the carriage structure as shown in FIGURE 6 and taken along reference line VIIVII thereof;

FIGURE 8 is a partial front elevational view of the carriage structure as shown in FIGURE 6, but with the stopping mechanism thereof in an extended or carriagestopping position; and

FIGURE 9 is a longitudinally sectioned View of the carriage structure as shown in FIGURE 8 and taken along reference line IX-IX thereof.

Referring now more particularly to FIGURES l and 5 of the drawings, the illustrative form of the invention shown therein includes, for the steel making operation, an oxygen furnace 10 filled with .a charge of material 12, with the open end 14 of the furnace shielded by a watercooled shield 16 having an opening 17 therethrough, through which is passed an oxygen lance 18. The lance 18 is supported upon a lance carriage 20 by means of mounting brackets 22, 24, which hold the lance 18 perpendicularly in this example. The carriage 20 is guided for rectilinear and perpendicular movement, in this arrangement, by means of pairs of spaced tracks 28, cooperating respectively with carriage wheels 27 and 29 and carried by an I-beam framework or the like 31 which is held outwardly from a support wall 32 or the like and means of upper and lower pivotally mounted arms 34 and 36. The pivotally mounted supporting frame 31 is displaced angularly by means of drive motor 35 mounted on the framework 31 intermediately of the pivoted arms 34, 36 and operating through gearing train 37, 38 enmeshed with gear segment 39, which is stationarily mounted on the wall structure 32, concentrically with the vertical axis of upper and lower pivot mountings 40 and 42.

The length of the vertically extending frame 31 and the tracks 28, 30 carried thereby is such that at the full line position of the carriage 20 (FIGURE 1) the lance 18 is raised to its full line or withdrawn position relative to the furnace 10, and at the chain line position of the carriage 20 the lance 18 is at its fully inserted or operative position, with its lower end extended into the refractory lined furnace 10.

In this arrangement the carriage 20 is supported by a pair of cables 44 which are dead ended or secured at the upper end of the pivoted frame 31 as denoted by reference character 46 (FIIGURE l). The cables 44 respectively pass under a pair of pulleys 48 rotatably mounted on the upper end of the carriage 20 and are wound upon a winch mechanism 50, which can be rotated in either direction by a reversible drive mechanism denoted generally at 52.

An adjustable clamp mechanism 54 operated by hand wheel 56 inthis example, is mounted on each of the supporting brackets 22, 24 for clamping engagement with lance 18. Mounted atop the upper supporting bracket 22 is suitable gas handling equipment denoted generally by reference character 58 and communicating with the upper end of the lance 18.

Referring now to FIGURES 2 and 4 of the drawings it will be seen that pairs of opposed slots 60 and 62 are spaced along the length of the vertical framework 31. In this example the lower edges 64 of each slot 60 or 62 form a series of stops spaced along the framework 31 for cooperation with a pair of allochirally shaped and mounted anchor members 66 and 68. The bottom edges 64 of the slots 60 and 62 desirably are reinforced by a like number of transversely extending channeled beam segments 70 which in this example are welded to the outer web surfaces of the I-beams 72 and 74 forming the vertical supports of the pivoted framework 31. As better shown in FIGURE 5 the channeled beam segments 70 desirably extend to engagement with the adjacent flange portions of the beams 72 and 74 where they can be secured as by welding. Thus, the stops 64-70 are adequately reinforced for absorption of the decelerational forces generated upon braking action of the anchor members 66, 68 when actuated to engage the stops 64-70 as described hereinafter.

The anchor members 66 and 68 are each pivotally mounted within an open ended hollow stop bar denoted generally by reference character 76. The stop bar 76 for example can be fabricated by welding together a number of elongated rectangular plates 78 and crossbraces 80, 81, and protrudes at each end through opposed slots 82 in the sidewalls of the carriage 20. The anchor members 66, 68 therefore are mounted on pivot pins 84 which extend between and are secured adjacent their ends to the side plates 78 of the stop bar 76. The stop bar 76 is mounted at each end thereof upon a relatively short angle iron segment 86 secured to the stop bar 76 by suitable fastening means such as welding or bolting and normally fastened at the lower end of the associated stop bar slots 82 by means of a shear pin 88. The shear pins 88 are sized such that upon actuation of the anchor members, as shown in FIGURE 4, the pins 88 are readily severed to permit the carriage 20 to descend a further distance within the confines of the stop bar slots 82. However, such distance is adequate for actuation of shock absorbers 90 which terminate free fall of the carriage 20 without the develop ment of undue or damaging decelerational forces, as described more fully hereinafter. Although fluid type shock absorbers 90 have been illustrated, it is contemplated that other shock absorber means such as coil or disc springs can be utilized.

In this example, the anchor members 66, 68 normally are maintained in their inactive positions as shown in FIGURE 2 by means of a suitable flexible cord or connection such as chain 92 secured at its ends to the inner end portions of the anchor members 66, 68 and passing over an intermediately and rotatably mounted wheel shaped to engage the cord, such as sprocket 94. The sprocket 94 can be mounted on a pair of depending brackets 96 therefor, which in turn are mounted upon a drawbar 98. The drawbar 98 in this example is secured at each end to a pair of slidably mounted draw bolts 100 or 102 respectively. The draw bolts 100, 102 are secured at their upper ends to a pulley supporting bar 104 on which the aforementioned carriage pulleys 48 are rotatably mounted. With this arrangement during normal elevating movements of a carriage 20 the slidably mounted draw bolts 100, 102 permit the drawbar 98 to engage the under side of the carriage crossbrace 106 to support the' carriage 20 during normal raising and lowering movements. This limited movement of the drawbar 98 relative to the carriage 20 causes the sprocket 94 to tighten the chain 92, which withdraws the anchor members 66, 68 to their inactive positions as shown in FIGURE 2 against the action of suitable biasing means such as coil springs 108.

In this example, the coil springs 108 are respectively mounted in tubular housings 110, the upper ends of which serve as stationary spring stops. The tubular spring housings 110 are respectively mounted upon the lower crossbraces 81 at the under side of the stop bar 76. A spring rod 112 is pivotally joined to each anchor member 66 or 68 as denoted by reference character 114 and at its other end to a movable spring stop 116 mounted for reciprocating movement within the tubular housing 110. A suitable aperture 113 is formed in each of the crossbraces 81 to accommodate the associated spring rod 112.

Referring now to FIGURE 4 of the drawings, upon severance of the supporting and elevating cables 44 the safety mechanism of our carriage structure becomes operative. In furtherance of this aim the biasing springs 108 expand to pivot the anchor members 66, 68 to their operative positions to engage an adjacent pair of the stop slots 60, 62, or alternatively depending on the location of the carriage 20 at that time, the adjacent surfaces of the web portions of I-beams 72 and 74 respectively, whereupon further free fall of the carriage 20 causes the outer ends of the anchor members 66, 68 to project through the firstencountered pair of slots 60, 62. At the same time the biasing springs 108 cause the drawbar 98 and associated components including the chain 92 to move downwardly relative the carriage 20, if it has not already done so immediately upon severance of the cables 44, until the pulley supporting bar 104 engages carriage crossbrace 118. At this position of the drawbar 98 and supporting bar 104 the chain 92 becomes slack as denoted by reference character 120 to ensure the proper positioning of the anchor members 66 and 68 in their operative positions as defined by stop members 122 engaging the lower edges of the anchor members respectively and secured to the side plates 78 of the stop bar 76.

Upon operative engagement in this manner of the anchor members 66, 68 with an opposed pair of the stops 64-70 spaced as aforesaid along the vertical length of the carriage guiding framework 31, the shear pins 88 which normally secure the stop bar 76 to the carriage framework are immediately severed as denoted by pin portions 88a and 88b in FIGURE 4. Upon this occurrence, which of course does not materially decelerate the carriage 20 in its free fall, the stop bar 76 is then coupled to the carriage 20, within the confines imposed by the stop bar slots 82, solely by engagement of its upper crossbraces 80 with the aforementioned shock absorbers 90 and particularly, in this example, by engagement respectively with the free outer ends of their piston rods 124, as better shown in FIGURE 2.

In furtherance of this purpose a suitable bearing pad 126 can be secured to each of the piston rods 124 for engagement with the associated one of the stop bar crossbraces 80. In this arrangement a pair of hydraulic shock absorbers 90 are utilized and their hydraulic systems are connected through suitable conduits, denoted generally by reference character 128, to a hydraulic accumulator tank 130. The pneumatic pressure or the like maintained in the accumulator tank 130 is such that the carriage structure is decelerated by further downward movement as defined by the length of piston stroke shown in FIGURE 2 of the drawing. Thus, the carriage 20 comes to rest at the inserted positions of the shock absorber piston rods against the stop bar 76, as illustrated in FIGURE 4, with the application of little or no impact forces to the carriage 20 or to the stop bar 76 and associated components of the vertical framework 31.

To restore our stopping mechanism to its ready position as illustrated in FIGURE 2, it is only necessary to attach new supporting cables 44 and to replace the shear pins 88. It will be understood, of course, that the opposed stops or arresting surfaces 64-70 and the associated slots 60, 62 can be spaced closer or farther apart along the length of the vertical frame 31, depending upon the required safety factor and the weight of the carriage 20 and other components. It is also contemplated that the vertical length of the slots 60 and 62 can be varied together with the size of the anchor members 66 and 68 depending upon the aforementioned factors in a given application of the invention and upon the biasing forces applied to the anchor members. Obviously, too, the slots 60, 62 can be eliminated and stop members such as the beam segments 74 can be provided on the adjacent web surfaces of the I-beams 72 and 74. Although the invention has been described with reference to a lance carriage, it will be apparent that our stopping mechanism is applicable to carriages supporting any type of load and mounted on vertical or relatively or steeply inclined guideways where personnel injury or equipment or load damage may result upon inadvertent release of the carriage.

Referring now to FIGURES 69 of the drawings, another form of the carriage and stopping mechanism of the invention is illustrated, wherein similar reference characters with primed accents note components similar to those of FIGURES 1-5. The arrangement of the latter figures thus includes a carriage 20' having a double-sheaved block 48' at the upper end thereof as viewed in the drawings, and, in this example, a heat shield denoted generally by reference character 132 at the lower end thereof. The sheave block 48 is mounted upon a bracket including a plurality of stub shafts 134 which extend longitudinally and slidably through the upper end of the carriage 20'. The lower ends of the shafts 134 desirably are secured to a drawplate 136 or the like and thence to a drawbar 138 composed of parallel spaced side members one of which has a guide slot 140 therein.

In this example, the upper axle 139 is inserted through the double-walled drawbar 138. Inner carriage wheels 141 are mounted respectively on the protruding outer ends of the axle 139. The upper end of spring bar 142 is slidably extended through an aperture in the lower end of the drawbar 138 and engages the slot 140.

The lower end of the spring bar 142 is slidably inserted through spring housing 144 and is then threadedly connected to a nut 146 forming part of couple 148.

The couple 148 is thus mounted for vertical reciprocation with the lower end of spring rod 142 between the flanges of stopbar 76', the upper flange 150 of which is pinned to the sides of the carriage 20 by means of angle brackets 86' and shear pins 88'. The outer ends of the couple 148 are pivotally connected to the inward extremities of a pair of anchor members or dogs 66' which in turn are pivotally mounted on the stopbar 76' by pins 84'. The dogs 66' thus cooperate with the slots 60' and crossbeam segments 70' as described previously in conjunction with FIGURES l5.

During normal operation of the carriage 20', the couple 148 and dogs 66' are restrained against the upper flange 150 of the stopbar 76' by the limited upward movements, owing to the weight of the carriage 20', of the sheave block 48', drawbar 138 and spring bar 142, with the latter engaging the lower end of the drawbar 138 by means of its upper stop 152. The relative movement of these components with respect to the carriage 20' is defined by the lengths of the stub shafts 134 and is delimited in the upper direction by engagement of the drawplate 136 with the upper end portion of the carriage 20. This action substantially fully compresses, in this example, oppositely directed biasing spring 154 which is positioned within the spring housing 144 and is restrained by the upper end thereof and by lower spring bar stop 156.

The spring stop 156 is positioned adjacent the lower, threaded portion of the spring bar 142. At the normal position of the stopbar 76', as shown by the position of shear pins 88', the upper surfaces of the drawbar 76' are lightly engaged by a pair of piston rods or plungers 124' forming part respectively of a pair of shock absorbers or the like 90'. The shock absorber housings or cylinders are rigidly secured to the carriage 20 and are coupled in fluid communication with an accumulator 130' through conduits 128' as described previously in connection with FIG- URES 1-5 of the drawings.

Referring now more particularly to FIGURES 8 and 9 of the drawings, a sudden release of the carriage weight, as by the severence of cables 44' or breaking of related lifting components of the carriage 20' or the like, permits the biasing spring 154 to move the spring rod 142 and related components including the couple 148 downwardly relative to the carriage 20' until sheave bracket 158 engages the adjacent top surface of the carriage 20" to terminate such downward movement. At such time the couple 148 is moved downwardly relative to the stopbar 76' to a point near the lower flange 160 thereof. However, this movement of the spring rod 142 and couple 148 and related components is not completed until the carriage 20 drops sufficiently to permit the outer ends of dogs 66' to engage and protrude through an adjacent pair of the slots At the lower ends of the slots 60 in the supporting beams 72 and 74, the outer end portions of the dogs engage the crossbeam segments 70, whereupon further descent of the stop bar 76' is immediately terminated. At such time the weight of the stopbar 76' then rests upon the pivot pins 84 of the dogs 66, further rotation of which is prevented by stop plates 162 mounted on the upper surface of the lower flange 160 of the stop bar 76'.

The sudden stopping of the stop bar 76' of course severs the shear pins 88 and causes the weight of the carriage 20 to be brought to a rest upon the stop bar 76 through the action of shock absorbers 90 in a manner similar to that described previously in connection with FIGURES 1-5 of the drawings.

We claim:

1. In a carriage mounted for ascending and descending movement along a pair of guideways having a plurality of stops spaced along the length thereof and pro viding arresting surfaces for engaging and holding said carriage, the combination comprising anchor means mounted on said carriage for movement between an inactive position and an active position of engagement with said stops, an elevating member movably mounted on said carriage, said elevating member movably mounted on said carriage, said elevating member being movable between an active position of engagement with said carriage to raise and lower said carriage when force is applied to said elevating member and an inactive position corresponding to the active position of said anchor means, means for coupling said elevating member to said anchor means and for retaining said anchor means in the inactive position thereof at the active position of said elevating member, biasing means coupled to said anchor means and to said elevating member for urging said anchor means to the active position thereof to engage said stops, said biasing means being active only upon failure of said raising and lowering force, a stop bar fixedly mounted on said carriage for subsequent detachment and movement, said anchor means being movably mounted on said stop bar, and shock-absorbing means for limiting any such subsequent movement of said stop bar.

2. The combination according to claim 1 wherein said anchor means include a pair of oppositely acting anchor members, said biasing means includes a separate biasing member for each of said anchor members, and said coupling means include a wheel rotatably mounted on said elevating member and a flexible cord passing over said wheel, the ends of said cord being connected to said anchor members respectively.

3. In a carriage and stopping mechanism therefor mounted for ascending and descending movement along guideways therefor having a plurality of spaced stops disposed along the length thereof and providing arresting surfaces for engaging and holding said carriage, the combination comprising retractable anchor means disposed between said carriage and said guideways and engageable with said stops to define a descending position of said carriage, a retractable drawbar member mounted for limited movement upon said carriage and engageable with elevating means for said carriage, means for coupling said drawbar member when so engaged to said anchor means to retain said anchor means in said retracted position thereof, biasing means coupled to said anchor means for urging said anchor means into engagement with said stops, said biasing means being operable upon disengagement of said elevating means from said drawbar member and movement of said drawbar member to its retracted position, a stop bar fixedly mounted on said carriage for subsequent detachment and movement, said anchor means being movably mounted on said stop bar, and shock-absorbing means for limiting any such subsequent movement of said stop bar.

4. The combination according to claim 3 wherein a stop bar is mounted on said carriage, means are included for pivotally connecting said drawbar member to said anchor means, said anchor means being pivotally connected to said stop bar so that movements of said drawbar relative to said stop bar produce corresponding movements of said anchor means to engaged and retracted positions thereof, said drawbar member being disposed to move said anchor means to their retracted positions when engaged with said elevating means, and biasing means are coupled between said drawbar member and said stop bar and directed so as to move said drawbar member relative to said stop bar in a direction to pivot said anchor means to their engaged positions upon disengagement of said drawbar member from said elevating means.

5. In a carriage and stopping mechanism therefor mounted for ascending and descending movement along guideways therefor having a plurality of spaced stops disposed along the length thereof and providing arresting surfaces for engaging and holding said carriage, the combination comprising retractable anchor means disposed between said carriage and said guideways and engageable with said stops to define a descending position of said carriage, a retractable drawbar member mounted for limited movement upon said carriage and engageable with elevating means for said carriage, means for coupling said drawbar member when so engaged to said anchor means to retain said anchor means in said retracted position thereof, biasing means coupled to said anchor means for urging said anchor means into engagement with said stops, said biasing means being operable upon disengagement of said elevating means from said drawbar member and movement of said drawbar member to its retracted position, a stop bar mounted upon said carriage structure, said anchor means and biasing means being mounted thereon, said stop bar being mounted for limiting movement upon said carriage structure but normally retained in an inactive position thereof relative to the retracted position of said anchor means by shear pins securing said stop bar to said carriage structure.

6. In a carriage and stopping mechanism therefor mounted for ascending and descending movement along guideways therefor having a plurality of spaced stops disposed along the length thereof and providing arresting surfaces for engaging and holding said carriage, the combination comprising retractable anchor means disposed between said carriage and said guideways and engageable with said stops to define a descending position of said carriage, a retractable drawbar member mounted for limited movement upon said carriage and engageable with elevating means for said carriage, means for coupling said drawbar member when so engaged to said anchor means to retain said anchor means in said retracted position thereof, biasing means coupled to said anchor means for urging said anchor means into engagement with said stops, said biasing means being operable upon disengagement of said elevating means from said drawbar member and movement of said drawbar member to its retracted position, a stop bar mounted upon said carriage structure, said anchor means and said biasing means being mounted thereon, said stop bar being mounted for limited movement upon said carriage structure and coupled to said carriage structure through shock absorber means, and said stop bar being disposed for relative movement with respect to said carriage structure upon engagement of said anchor means with said stops against the action of said shock absorber means until said carriage structure comes to rest against said stop bar and anchor means.

7. In a carriage and stopping mechanism therefor mounted for ascending and descending movement along guideways therefor having a plurality of spaced stops disposed along the length thereof and providing arresting surfaces for engaging and holding said carriage, the combination comprising retractable anchor means disposed between said carriage and said guideways and engageable with said stops to define a descending position of said carriage, a retractable drawbar member mounted for limited movement upon said carriage and engage able with elevating means for said carriage, means for coupling said drawbar member when so engaged to said anchor means to retain said anchor means in said retracted position thereof, biasing means coupled to said anchor means for urging said anchor means into engagement with said stops, said biasing means being operable upon disengagement of said elevating means from said drawbar member and movement of said drawbar member to its retracted position, said carriage having slot means therein directed generally transversely of said guideways, a transversely extending stop bar slidably mounted in said slot means for longitudinal movement relative to said carriage and in a direction generally parallel to said guideways, and said anchor means including a pair of anchor members pivotally mounted on said stop bar adjacent the ends respectively thereof.

8. The combination according to claim 7 characterized in that said stop bar is secured to a pair of spaced bracket members which in turn are secured to said carriage structure adjacent the lower ends of said slot means by shear pins respectively.

9. The combination according to claim 7 characterized in that a first pair of stop members are mounted on said stop bar to define the retracted positions respectively of said anchor members, and a second pair of stop members are mounted on said stop bar to define the engaged positions respectively of said anchor members.

10. The combination according to claim 7 characterized in that shock absorber means are extended between 10 said carriage structure and said stop bar, said shock absorber means in the relaxed position thereof defining the inactive position of said stop bar in said slot means.

11. The combination according to claim 10 characterized further in that said shock absorbing means include a pair of hydraulic cylinders having their piston rods engaging a pair of stop members mounted on said stop bar, said stop members in addition defining the retracted positions respectively of said anchor members, and said hydraulic cylinders are coupled through conduit means to a common hydraulic accumulator tank mounted on said carriage.

References Cited UNITED STATES PATENTS 579,797 3/1897 Gray 18782 889,833 6/1908 Wallingford 18782 1,057,303 3/1913 Trepa 187-82 1,219,050 3/1917 Sugg 18782 3,007,691 11/1961 Rinesch et a1 266-342 CARLTON R. CROYLE, Primary Examiner.

ALLAN D. HERRMANN, Assistant Examiner.

US. Cl. X.R. 266-34 

